Injection press apparatus

ABSTRACT

This new apparatus includes or relates to an injection molding press wherein injection means including a cylinder and poweractuated piston is provided for forcing a plastic material into a mold cavity and wherein a slidably positioned injection nozzle connects the injection cylinder to a charge sprue provided in the mold. Special means position the injection nozzle for limited sliding movement in sealed relationship with the injection nozzle whereby the injection nozzle can be operated and will function satisfactorily under varied injection molding pressures and conditions. The invention further relates to an automatic power timer and cycle control means connecting to the injection means and to mold positioning means whereby the pressure exerted on the mold for mold closing action can be momentarily relieved to permit entrapped air to escape during an injection molding cycle.

United States Patent [72] Inventor Nyles V. Reinfeld 610 Treeside Ave.,Akron, Ohio 44313 [21] Appl. No. 791,381 [22] Filed Jan. 15, 1969 [45]Patented Jan. 4, 1972 [54] INJECTION PRESS APPARATUS 5 Claims, 2 DrawingFigs.

[52] US. Cl 425/157, 425/247 [51] Int. Cl 1329f H03 [50] Field of Search18/30 CK, 30 CR, 30 F0, 301, 30 NR, 30 NV, 30 NM, 30 NP, 30 NN, 30 CM,30 LV, 30 LM, DIG. 2

l 56] References Cited UNITED STATES PATENTS 2,187,212 l/l940 McMillin18/30 CK 2,588,662 3/1952 Sayre 18/16 C 3,226,769 1/1966 Williamson eta1. 18/30 CK 3,509,600 5/1970 Noble 18/30 CK Assistant Examiner-Michael0. Sutton Attorney-Oldham & Oldham ABSTRACT: This new apparatus includesor relates to an injection molding press wherein injection meansincluding a cylinder and power-actuated piston is provided for forcing aplastic material into a mold cavity and wherein a slidably positionedinjection nozzle connects the injection cylinder to a charge sprueprovided in the mold. Special means position the injection nozzle forlimited sliding movement in sealed relationship with the injectionnozzle whereby the injection nozzle can be operated and will functionsatisfactorily under varied injection molding pressures and conditions.The invention further relates to an automatic power timer and cyclecontrol means connecting to the injection means and to mold positioningmeans whereby the pressure exerted on the mold for mold closing actioncan be momentarily relieved to permit entrapped air to escape during aninjection molding cycle.

mzmmm 4m TIMER & CONTROL BOARD INVENTOR. NYLES V REINFELD M MMWATTORNEYS.

INJECTION PRESS APPARATUS The present invention relates to injectionmolding presses and to improved injection nozzle means for the press andwherein the press injection nozzle can have slight movement in itspositioning means and maintain sealed relationship between the injectioncylinder and an associated mold to compensate for different operatingpressures in a mold during a mold filling cycle.

Heretofore there have been various efforts made to provide for thebumping of molds during injection molding processes. This bumping of themolds, insofar as I am aware, has primarily been provided after thecavity has been filled with injected material. In all events, therealways is a problem in any injection molding operation of removing anyair entrapped in the mold cavity and tending to be expelled therefromwhen material is forced into the mold.

The general object of the present invention is to provide an improvedinjection molding apparatus including a slidably positioned nozzlewherein improved mold filling action can be obtained.

Another object of the invention is to provide a special injection nozzlein an injection press and novel control means whereby entrapped airwithin a mold can be permitted to escape therefrom during a moldinjection cycle.

A further object of the invention is to combine a special injectionnozzle in an injection press with novel control means for the presswhereby the mold sections can be cracked apart momentarily during aninjection cycle without loss of injection material or any seriousinterference with the mold injection cycle.

A specific object of the invention is to provide an injection nozzle atleast a portion of which has limited axial movement in the press whereinthe nozzle remains in sealed engagement with the injection cylinderduring such sliding movement and wherein the sliding movement can beprovided to absorb some pressure differentials in the injection materialduring the injection cycle.

Another specific object of the invention is to provide an improvedcontrol and timer means in an injection molding press whereby theinjection cycle can include a momentary release of the mold closingpressure to permit an instantaneous mold release or cracking and closingaction to permit entrapped air to escape.

The foregoing and other objects and advantages of the invention will bemade more apparent as the specification proceeds.

Reference is made to the accompanying drawings wherein:

FIG. 1 is an elevational view of a typical injection press with controlmeans of the invention shown in diagrammatic form associated therewith;and

FIG. 2 is an enlarged fragmentary vertical section taken on line 2-2 ofFIG. 1.

When referring to corresponding members shown in the drawings andreferred to in the specification, corresponding numerals are used tofacilitate comparison therebetween.

In general, the present invention can be said to relate to thecombination of a special injection means in a plastic injection moldingpress wherein the discharge nozzle has a limited sliding movement in anaxial direction with relation to the remainder of the injection meansand which nozzle will remain in sealed engagement with the remainder ofthe injection means during such sliding movement whereby the position ofthe nozzle can change with varied pressure conditions applied thereto,and wherein the injection molding press is provided with hydraulicallyactuated piston and cylinder means for controlling the position of amovable mold in the press and a control valve or equivalent means can becracked open for an instant during a mold injection cycle to permitentrapped air to escape from the mold press followed by an immediatereapplication of hydraulic pressure to return the molds to fullyoperative closed conditions.

In the accompanying drawings, a plastic injection molding press isindicated as a whole by the numeral 10. This press is particularlydesigned for molding natural and synthetic rubbers by an injectionmolding action, but other elastomer materials can be similarly processedin the press. if desired. The press 10 includes a frame 11 having a topbolster or platen 12 fixedly secured thereto, and a movable platen 13 issuitably slidably positioned on a portion of the frame of the press sothat a mold section 14 operatively carried on the movable platen can bebrought into engagement with a mold section 15 operatively carried bythe top platen 12. The mold sections 14 and 15 are suitably positionedon the associated platens 12 and 13 in any desired manner whereby themold sections will be abutted together under injection moldingconditions to fill a mold cavity defined therebetween with plasticinjection material.

The movable platen 13 is controlled in this position on the frame 11 byany conventional means, and usually a double hydraulic cylinder andpiston combination is provided in the press, or equivalent means car beused, whereby the movable platen 13 and the mold section secured theretocan be forced to abut against the mold section 15 under predeterminedoperating conditions. While only one cylinder 16 is shown with a piston17 being indicated therein, in many instances, it is conventional to usetwo pistons for controlling the movable platen 13, in the manner shownin expired U.S. Pat. No. 2,191,882 to Mr. Ernst. The drawing shows ahydraulic pressure fluid supply line 18 that connects to a bottomportion of the cylinder 16 and pressure flow of hydraulic fluid to thecylinder 16 is regulated by means of a conventional control means, suchas a threeor fourway solenoid controlled valve 19 that connects by aline 20 to a suitable source of hydraulic pressure (not shown). Thevalve 19 also connects to an exhaust line or conduit 21 whereby when thevalve 19 is actuated so as to be positioned in its socalled openposition, or exhaust position, fluid will drain from the cylinder 16through valve 19 to the exhaust line 21.

FIG. 1 of the drawings also clearly shows that a substantially vconventional timer and control board indicated by the numeral 35 is alsoprovided for the press 10. Such timer and control board has any suitablepower supply provided therefor and it connects by a pair of leads 36 and37 to the valve 19 whereby when the timer or control functions asestablished by the control board 35 are so established, control impulsesor voltages can be transmitted by the leads 36, 37, to control thepositioning or setting of the solenoid valve 19. Thus, upon onepredetermined set of operating conditions, the valve 19 is actuated tocause pressure fluid from the line or conduit 20 to flow through theline 18 and provide platen closing movement for the movable platen 13and any mold section associated therewith However, upon another impulseor control signal to the solenoid valve 19, the valve will be set toconnect the line 18 to the exhaust line 21 whereby pressure set upwithin the cylinder 16 will be almost instantaneously dissipated orgreatly reduced whereby a mold opening action will start to occur almostimmediately upon change of the valve setting.

The timer and control board 35 also connects to an injection means 40suitably fixedly secured to the top platen 12. Such injection meansincludes at least a cylinder 41 that has a power actuated piston 42slidably carried therein whereby when pressure is provided to thecylinder 41 through a supply tube or line 43, the piston 42 will beforced axially downwardly to discharge material from the injectioncylinder 41 as hereinafter described. The pressure supply line 43normally provides hydraulic operative pressure from a conventionalsource thereof (not shown) and wherein a solenoid valve 44 or equivalentmeans is provided in the pressure line 43 to control actuation of thepiston 42 at desired times. Leads 45 and 46 connect the solenoid valve46 or equivalent member to the control and timer board 35 so thatcontrol or operative impulses can be sent to the solenoid valve 44 andeffect actuation thereof when mold filling cycle conditions are set upand it is desired to produce a mold injection action to form the articlein the mold.

FIG. 2 of the drawings shows that the injection means 40, andparticularly the cylinder 41 thereof normally extends down through asuitable hole or opening 50 provided in the top platen or bolster 12.Any suitable type of support plate 51 is suitably secured to the lowersurface of the top bolster 12 and this injection means 40 is secured tothe support plate 51 and top platen or bolster 12 in any desired manner(not shown). Preferably layer of insulation 52 is positioned below thesupport plate 51 and coverplate 53 is suitably secured in position belowthe layer of insulation 52. Normally, a plurality of suitable heaterunits or means 54 are provided in recesses provided in a spacer or moldbackup plate 55 that is secured to the top bolster 12 intermediate itand the fixed mold section attached to the lower surface of such backupplate. The provision of the heater means in association with theinjection means 40 is conventional and any suitable insulation andheater means may be provided in association with any desired portions ofthe injection cylinder 41.

As an important feature of the present invention, at the lower end ofthe injection cylinder 41, an injection nozzle 60 is provided and it issecured to the injection cylinder as by a suitable sleeve, tubularmember, or positioning nut 61. The nut 61 has an enlarged axially innerend 62 which is in threaded engagement with the discharge end of theinjection cylinder 41. The nut 61 is relatively long in an axialdirection and this elongate nut slidably receives the injection nozzle60 therein with the axially outer end of the injection nozzle, inrelation to the injection means 40, protnrding from and beyond the loweror axially outer end of the nut 61. The nozzle 60 has a flange 63 formedthereon adjacent its axially inner end and such flange 63 normally willseat on a shoulder 64 facing axially inwardly of the nut 61 and providedin the enlarged upper end thereof. The axially inner end of theinjection nozzle 60 has a conically shaped opening 65 that can convergesinwardly of the nozzle and connects to a bore 66 extending the length ofsuch nozzle.

In order to position the nozzle 60 properly in the apparatus, and to aidin feeding material thereinto, a lock member or collar 67 is provided.This collar 67 abuts against a shoulder 68 formed at the discharge endof the cylinder 41 adjacent the discharge opening therein, and suchcollar 67 is forced against the shoulder 68 by the axially inner end ofthe nut 61 as it is brought into pressure contact therewith by thethreaded engagement of the nut with the injection cylinder. An axiallyoutwardly converging bore 69 is formed in the collar 67.

FIG. 2 of the drawings clearly shows .that the nut 61 and collar 67 forma confining chamber to secure the injection nozzle 60 in sealed, butsliding engagement with the cylinder 41. The injection nozzle 60 has anenlarged cylindrically shaped inner end section 70 formed thereon andsuch section 70 is in effectively sealed, tight, sliding metaltometalcontact with a tubular section 71 formed at the axially outer end of thecollar 67. FIG. 2 on the left side section thereof indicates theposition of the injection nozzle 60 when operative pressure is fullyapplied to such injection nozzle, but when no mold closing pressure hasbeen applied to the mold section 15. On the righthand side or section ofFIG. 2, the position of the injection nozzle 61) is shown when fullclosing pressures have been applied to the mold sections and the nozzle60 has been forced axially backwardly up toward the injection means 40.Hence, whenever pressure on the axially outer end of the injectionnozzle 60 is released or changed, such nozzle can adjust its axialposition in the injection means and retain sealed engagement therewith.For example, when the mold sections 14 and 15 are cracked open, there isa tendency for the injection nozzle 60 to move axially inwardly of thepress, and it can move toward the position shown on the left side ofFIG. 2 and still maintain substantially continuous injection moldingaction during a mold separation interval in an injection molding cycle.

It will be seen that the axially outer end of the injection nozzle 60protrudes beyond the nut 61 and that such nozzle has a contoured surface72 that is adapted to seat on a sprue 73 formed complementary in shapeto the end of the nozzle. Thus, a tight, but effective pressureretaining seat is obtained to lead the injected material into thedistributing sprues formed in the mold sections being processed.

The bumping action of the mold sections 14 and 15 on the inject cyclepreferably occurs near the end thereof. The timer and control means 35are programmed so that they actuate the solenoid valve 44 or othersimilar means to shutoff injection action temporarily while the moldsare cracked apart and brought back together under full pressure moldclosing conditions.

Suitable means and controls (not shown) are provided to return thepiston 42 to retracted position and to supply injection material to theinjection means 40.

By a combination of the novel injection means and slidable injectionnozzle in the press of the invention, together with the novel controlmeans provided, an improved injection molding action can be obtainedwith a minumum of spoilage of the formed part by air entrapped in themold cavity. Hence, it is believed that the objects of the inventionhave been achieved.

While one complete embodiment of the invention has been disclosedherein, it will be appreciated that modification of this particularembodiment of the invention may be resorted to without departing fromthe scope of the invention as defined in the appended claims.

What is claimed is:

1. In an elastomer injection molding press including a frame having afixed platen therein adapted to have a mold section operatively securedthereto, injection means including a cylinder having a discharge endoperatively secured to said fixed platen, the improvement comprising atubular means secured to said cylinder at its discharge end, aninjection nozzle slidably positioned within said tubular means andextending to and through said platen to any mold section securedthereto, said nozzle having limited axial movement in said tubular meansand being in sealed engagement therewith, said tubular means comprisingan elongate nut secured to said cylinder at its discharge end, a nutcollar operatively positioned in said cylinder to extend across the borethereof by said nut, said nut collar having a cylindrical section in itsaxially outer end and an axially inwardly tapering section at itsaxially inner end connecting to said cylindrical section, and saidinjection nozzle has a flange on its axially inner end slidably confinedbetween said nut collar and a part of said nut for limited axialmovement of said nozzle.

2. In an injection press including a frame having a fixed platentherein, a movable platen slidably carried by said frame parallel tosaid fixed platen, hydraulic piston and cylinder means engaging saidmovable platen to move it towards and away from said fixed platen, amold member operatively engaging said fixed platen and a mold sectionoperatively carried by said platen and being movable into engagement formolding action in a molding cavity formed thereby, an injection meansincluding an outlet member having a nozzle member operatively connectingto said fixed platen and said mold member thereon for forcing materialinto the mold cavity, and power means for actuating said injectionmeans, the improvement comprising automatic power timer and cyclecontrol means connecting to said power means to control materialinjection, hydraulic pressure supply means connecting to said cylinderto control mold closing movement of said movable platen, a control valveconnected in said hydraulic supply means to control hydraulic pressureflow to and exhaust from said cylinder, circuit means connecting saidcontrol valve to said power and control means to actuate said controlvalve for pressure release action and to return pressure applicationrapidly at least once for each operating cycle of the press beforecompletion of such cycle, and means positioning said nozzle member,injection means member, and mold member on said fixed platen in sealedrelationship but providing for some movement between two of said memberswithout breaking the seal therebetween.

3. In a molding press as in claim 1, the provision of a movable moldplaten, a hydraulic actuated means to control the position of saidmovable mold platen, a control means for said platens and being movableinto engagement for molding action in a molding cavity formed thereby,an injection means including a piston secured to said frame and having anozzle means operatively connecting to said fixed platen and the moldsection thereon for forcing material into the mold cavity power meansfor actuating said injection means, the improvement comprising automaticpower timer and cycle control means connecting to said power means tocontrol material injection, hydraulic pressure supply means connectingto said cylinder to control mold closing movement of said movableplaten, a control valve connected in said hydraulic supply means tocontrol hydraulic pressure flow to and exhaust from said cylinder,circuit means connecting said control valve to said power and controlmeans to open said control valve for pressure release and to close itrapidly for pressure application at least once for each operating cycleof the press before completion of such cycle, and means positioning saidnozzle for limited sliding movement in said injection means in sealedassociation therewith.

5. In an injection press as in claim 4 where said automatic power timerand cycle control means includes control mem bers connected to saidpower means to interrupt actuation of said injection means when saidcontrol valve is opened for pressure release and until mold closingaction reoccurs.

1. In an elastomer injection molding press including a frame having afixed platen therein adapted to have a mold section operatively securedthereto, injection means including a cylinder having a discharge endoperatively secured to said fixed platen, the improvement comprising atubular means secured to said cylinder at its discharge end, aninjection nozzle slidably positioned within said tubular means andextending to and through said platen to any mold section securedthereto, said nozzle having limited axial movement in said tubular meansaNd being in sealed engagement therewith, said tubular means comprisingan elongate nut secured to said cylinder at its discharge end, a nutcollar operatively positioned in said cylinder to extend across the borethereof by said nut, said nut collar having a cylindrical section in itsaxially outer end and an axially inwardly tapering section at itsaxially inner end connecting to said cylindrical section, and saidinjection nozzle has a flange on its axially inner end slidably confinedbetween said nut collar and a part of said nut for limited axialmovement of said nozzle.
 2. In an injection press including a framehaving a fixed platen therein, a movable platen slidably carried by saidframe parallel to said fixed platen, hydraulic piston and cylinder meansengaging said movable platen to move it towards and away from said fixedplaten, a mold member operatively engaging said fixed platen and a moldsection operatively carried by said platen and being movable intoengagement for molding action in a molding cavity formed thereby, aninjection means including an outlet member having a nozzle memberoperatively connecting to said fixed platen and said mold member thereonfor forcing material into the mold cavity, and power means for actuatingsaid injection means, the improvement comprising automatic power timerand cycle control means connecting to said power means to controlmaterial injection, hydraulic pressure supply means connecting to saidcylinder to control mold closing movement of said movable platen, acontrol valve connected in said hydraulic supply means to controlhydraulic pressure flow to and exhaust from said cylinder, circuit meansconnecting said control valve to said power and control means to actuatesaid control valve for pressure release action and to return pressureapplication rapidly at least once for each operating cycle of the pressbefore completion of such cycle, and means positioning said nozzlemember, injection means member, and mold member on said fixed platen insealed relationship but providing for some movement between two of saidmembers without breaking the seal therebetween.
 3. In a molding press asin claim 1, the provision of a movable mold platen, a hydraulic actuatedmeans to control the position of said movable mold platen, a controlmeans for said hydraulic actuated means to withdraw pressure therefromfor a predetermined instant during a mold filling cycle and then toreapply said pressure thereto.
 4. In an injection press including aframe having a fixed platen therein, a platen slidably carried by saidframe parallel to said fixed platen, hydraulic piston and cylinder meansengaging said platen to move it towards and away from said fixed platen,a mold section operatively carried by each of said platens and beingmovable into engagement for molding action in a molding cavity formedthereby, an injection means including a piston secured to said frame andhaving a nozzle means operatively connecting to said fixed platen andthe mold section thereon for forcing material into the mold cavity,power means for actuating said injection means, the improvementcomprising automatic power timer and cycle control means connecting tosaid power means to control material injection, hydraulic pressuresupply means connecting to said cylinder to control mold closingmovement of said movable platen, a control valve connected in saidhydraulic supply means to control hydraulic pressure flow to and exhaustfrom said cylinder, circuit means connecting said control valve to saidpower and control means to open said control valve for pressure releaseand to close it rapidly for pressure application at least once for eachoperating cycle of the press before completion of such cycle, and meanspositioning said nozzle for limited sliding movement in said injectionmeans in sealed association therewith.
 5. In an injection press as inclaim 4 where said automatic power timer and cycle control meansincludes control members connected tO said power means to interruptactuation of said injection means when said control valve is opened forpressure release and until mold closing action reoccurs.